It is known that radiation or lighting systems using LEDs and/or OLEDs will perform better at low temperatures. Therefore, each such lighting system will have a cooling system to limit the temperature of the LEDs and/or OLEDs.
When using radiation emitting devices for application near mammal tissue, it is very important to control and limit the temperature of the irradiated tissue. In general, thermal losses in terms of residual heat from LED and/or OLED devices will be removed via passive or active cooling, e.g., a heat sink with or without fan, to the environment. In case such a system is not desirable, then the electrical power input to the LEDs and/or OLEDs may instead be limited, such that the heat produced by the LEDs and/or OLEDs does not raise the tissue temperature above acceptable levels.
Solutions suggested in the prior art all intend to remove heat from the radiation emitting device to the ambient by using heat sinking, as, e.g., the flexible illuminator suggested in U.S. Pat. No. 6,290,713. However, this solution lacks efficiency when radiation emitting devices for application near mammal tissue are discretely worn under clothing, which will limit heat dissipation to the environment.
Safety is very important with respect to medical devices, specifically also for devices that are used in direct contact with mammal tissue, such as human skin. It must be guaranteed that in case of a device failure, no risks for the user/patient are induced.